Question

Why cant i do something like this?

This is the proerty in the logger class

public Dictionary<string, string> customProperties
        { get; set; }

This is the property in the interface…

 Dictionary<string, string> customProperties
        { get;  set; }

and then call it like this…

DatabaseLogger.ILogger logger = new DatabaseLogger.Logger();

logger.customProperties.Add("companyName", "Company");
logger.customProperties.Add("application", "application");

I am getting a NullReferenceExcpetion – how can I avoid it?

Answer 1

The only thing missing is initialization of the property – it is null otherwise (meaning that calling Add on it will throw a NullReferenceException).

DatabaseLogger.ILogger logger = new DatabaseLogger.Logger();

logger.customProperties = new Dictionary<string, string>();
logger.customProperties.Add("companyName", "Company");
logger.customProperties.Add("application", "application");

Though this might be better done in the Logger constructor:

public Logger()
{
  customProperties = new Dictionary<string, string>();
}